Natalie Certain says that every week, veteran racers retire or get fired to make room for the next generation racers. However, the season was almost over when more next generation racers started to push out the stock cars, so veteran racers leaving every week is impossible.
At Thunder Hollow, Cruz (under the name Frances Beltline) has the number #20 sprayed on her right side. When we see her during the talk with Smokey and the other veterans, it is now on her right side. Later she has it spray-painted on both sides when practicing with McQueen (in order to substitute for Jackson Storm, who's racing number is also #20) but this is after McQueen talks to Smokey.
In Cars 2, McQueen raced around the world in the World Grand Prix. If Sterling is McQueen's most advocate fan, how did he not know about McQueen competing in that race, let alone having pictures FROM it?
During the scene where Mater has sneezed and his tow cable comes undone, he says to, "watch your step". Since they're cars, they do not step like humans do. This therefore could reveal that cars killed humans (since they can talk and blink like humans can).